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The present study investigated the antifungal activity of octanal against Penicillium italicum and P. digitatum. Results showed that octanal exhibited strong antifungal activity against the test pathogens in a dose-dependent manner. Scanning electron microscopy observation revealed that octanal obviously altered the morphology of P. italicum and P. digitatum hyphae by causing the loss of cytoplasm and distortion of mycelia. A rapid increase in the membrane permeability of P. italicum and P. digitatum was observed after treated with octanal at minimum inhibitory concentration or minimum fungicidal concentration, evidenced by the release of cell constituents, the extracellular conductivity and the extracellular potential of hydrogen. In addition, octanal apparently induced a decrease in total lipid contents of P. italicum and P. digitatum cells. These results suggested that the antifungal activity of octanal against P. italicum and P. digitatum can be attributed to the disruption of the cell membrane integrity and the leakage of cell components.

BackgroundPlant essential oils could act effectively against postharvest diseases, α-terpineol, a typical terpenoid of plant essential oils, exhibited strong antifungal activity in against Penicillium italicum, but the possible action mechanism remains undetermined. In present study, α-terpineol was evaluated for antibacterial activity against Penicillium digitatum along with the mode of their antibacterial action.ResultsThe results showed that mycelial growth of P. digitatum was strongly inhibited by α-terpineol, with the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of 2.00 and 8.00 µl/ml, respectively. Scanning electron microscopy observation revealed that α-terpineol obviously altered the morphology of P. digitatum hyphae by causing the loss of cytoplasm and distortion of mycelia. A rapid increase in the membrane permeability of P. digitatum was observed after treated with MIC or MFC of α-terpineol, evidenced by the release of cell constituents, the extracellular conductivity, and the extracellular pH. In addition, α-terpineol apparently induced a decrease in total lipid contents of P. digitatum cells, indicating the destruction of cell membrane structures after treatment.ConclusionsBased on our study, α-terpineol might affect the cell wall synthesis and lead to the disruption of cell wall. The cell wall disruption affected fungal morphogenesis, the integrity of membrane and leakage of intracellular components, these results suggested that α-terpineol treatment inhibited the growth of P. digitatum.